Electrical insulator



4, 1953 H. KREISLER ELECTRICAL INSULATOR Filed Feb. 21, 1951 II I I I ([+1]. w l mmllni INVENTOR. HER/MN K/m/sLER I. 5 Hr roe/v57 E ix! a FIG. 3

Patented Aug. 4, 1953 UNITED STATES PATENT OFFICE ELECTRICAL INSULATOR Herman Kreisler, New York, N. Y.

Application February 21, 1951, Serial No. 212,185

.2 Claims. (01. 174-207) (Granted under Title 35, U. S. Code (1952),

sec. 266) of the type for attachin tension cable.

The invention, for example, may be embodied in an insulator for securing a guy line to a mast or the like superstructure that supports electrically energized equipment. A typical example of application of the invention is in rigging for a radar antenna mast on a ship.

The present invention is directed to an insulator comprising a block of dielectric material,

and comprising an insert of metal or the like material positioned in the block for engagement with a tension cable which is attached to the insulator. The metal insert has greater strength than the dielectric material of the insulator, and

it absorbs the physical stress applied by the cable. Stress distribution by the insert to the dielectric material of the insulator enables the insulator to support the load applied by the cable more effectively. I

The surface contour of the insert, and contours of surfaces of contact between the dielectric block and the insert, enables the insert to absorb and dissipate stresses applied by the cable under tensile load, as also ambient stresses incident to conditions under which the insulator is used. For example, shock loads and fatigue stresses that are enerated in a rigging by atmospheric storms are absorbed by the insert with less destructive effects on the dielectric material of the insulator.

The principles of the invention, and the disclosed practical embodiment thereof, will be clear from the accompanying drawing, to which attention is now directed.

1 In the drawing Fig. l is an elevation, illustrating an insulator embodying the invention as it appears in use,

Fig. 2 is an enlarged elevation of the insulator of Fig. 1,

Fig. 3 is a cross-sectional elevation, taken on line 3-3 of Fig. 1, and Fig. 4 is a detail in perspective illustrating an insert of the insulator of Fig. 2.

The insulator of the invention is adapted for a tension cable ll, Fig. 1, to .be attached thereto. In accordance with known prior-art practice, the tension cable H is formed to comprise the loop I2 at its terminal end by means of which the attachment is made.

The insulator comprises a block [5 of dielectric material, which is formed to include a groove l6, which is contoured convexly arcuate in accordance with the arcuate contour of the loop l2. An insert I! of metal or the like material is positioned in the groove [6 for engagement with the cable H.

The insert I! comprises a cable-contacting surface 20 and an opposed surface for contact with the dielectric block IS.

The cable-contacting surface 20 constitutes a trough which is laterally contoured concave, and which is sized for a matching fit with the cable ll. As seen in Fig. 3, the trough 20 in cross-section comprises a semi-circular concave portion, and straight sides 2| extending tangentially away from the semi-circular portion beyond the median diameter of the cable H. The sides 2| are spaced apart at least a distance equal to the diameter of cable H, and are preferably parallel. This specific structure of the cablecontacting surface comprising the trough 20 causes the cable to seat firmly in the trough and inhibits relative movement between the cable loop l2 and the insert l1.

Lengthwise of the cable H, and along the cable loop l2, the trough 20 is curved convexly arcuate in conformance with the contour of the cable loop.

The tensile load on cable ll becomes resolved into a lengthwise stress indicated by arrow 22, Fig. 3, and opposed lateral stresses indicated by arrows 23, the opposed lateral stresses being incident to the tendency of the loop 12 to collapse under the tensile load on the cable I I. The insert I1 is extended to comprise an intermediate portion that supports the lengthwise stress 22 under compression, and two side portions beyond opposite ends of theintermediate portion which support the lateral stresses 23 also under compression. The intermediate and side portions of the trough 20 along cable loop I2 are not positively defined, but instead they merge into each other, and they are curved smoothly continuously of each other and follow a contour that conforms with the design characteristics of loop 12. It is preferred, however, that the side portions of the trough 20 along loop l2 are curved smoothly continuously of each other and extend towards each other beyond the points where the legs 24 of the loop 12 are directed tangentially away from the curved portion 26 of the loop I2. Thus, the extent of the trough 20 along loop I2 is suflicient for the legs 24 of the loop to be positionedaway from, and out of 3 contact with, the base of the trough 20 at the opposite ends 21 of the insert H.

The insert l1 comprises a surface which contacts the dielectric block l and this surface comprises the bottom component 28 and two side components 29, which are disposed in opposed relationship with the cable-contacting surface 20, and which are coextensive therewith along the loop 12.

Laterally, the bottom component 28 of the dielectric-contacting surface is square, and along the loop [2 it follows the arc of a circle the center of which intersects the lineof. tension of the cable ll. Being square in the transverse direction the bottom component 28 is cylindrical, and the axis of the cylinder thereof is perpendicular to the line of cable tension.

The curvature of the trough 20 along the loop 12 is preferably also circular, and, as is seen in 'Fig. 3, the circle of trough 28 is coaxial with the cylinder of component 28 of the opposed dielectric-contacting surface.

The side components 29 of the block-contacting surface of insert il comprise side surfaces extending away from respective opposite side edges of bottom component 25, components 29 being directed outwardly of the curvature of loop l2 towards juncture with the cablecontacting surface 20. In the disclosed embodiment, the surfaces of side components 29 are flat.

The bottom component 28 is wider than the trough 20, and the area of pressure contact against the dielectric material is extended accordingly. Juncture between the cable-contacting surface 2!} and the dielectric-contacting sur- A face 23, 29 is through the peripheral face 38 which, in the disclosed embodiment constitutes cylindrical surfaces of like diameter extending each from a side H of trough 23 to its adjacent side component 29, the cylinder of surfaces 39 being coaxial with the cylindrical bottom surface 28.

The arcuate groove 16 of the dielectric block 15 is contoured for precise matching fit with the block-contacting surface 28, 29 of the insert i1, and accordingly comprises a cylindrical bottom component companion to the bottom component 23 of the insert, and side components respectively companion to the several side components 29 of the insert. To be certain of intimate contact and uniform pressure distribution throughout areas of contact between companion surfaces of the insert I! and groove 16 it is sometimes desirable, depending upon the manufacturing techniques for producing insulators, to roughen the bottom component 28 of the dielectric-contacting surface of the insert l! as seen in Fig. 4, and to apply an adhesive between companion contacting surfaces of the insert H and groove 16, the adhesive serving the purpose of a molded matrix.

The contour of groove it may be produced exactly to precise dimensions in the operation of molding the block [5, or the insulator may be molded to include the insert I"! in the molding operation of the block l5 for more intimate matching. fit. However, the invention is not directed .to the process of producing the insulator of the invention. It is only important that, by whatever manufacturing process is employed, the companion surfaces of groove I 6 and corresponding components 28 and 29 of insert ll .be precisely contoured for matching fit with each other.

Stress applied by the cable ll being under tension is absorbed by the metallic insert l1, and is dissipated thereby to reduce the stress on the block I5 of dielectric material which has less strength. The area of stress distribution is enlarged by the extended companion areas of contact between insert l1 and groove 16, and all the stress applied to the block [5 is in compression. Close contact between the cable loop l2 and the trough 20, and also between components 28 and 29 and companion components of the groove I 6, reduces the stresses applied to the dielectric block to those from tension on cable H plus the ambient stresses caused by atmospheric storms.

The groove l6 of the dielectric block [5 is extended at 33 beyond the terminating ends 21 of insert l1, and the contour of the groove l5 beyond ends 21 of insert I! to 33 is continuous of the bottom and side components for matching fit with components 28 and 29 of the insert. This allows for thermal expansion of the insert H, the material of which usually has a coefficient of thermal expansion greater than the coefficient of expansion of the dielectric material of block l5.

Beyond the surfaces 33 along the two legs 24 of loop l2, the groove I6 is contoured at its bottom 34, Figs. 2 and 3, to extend continuous with the base of the trough of the cable-contacting surface of insert l1, and at its sides is contoured to be smoothly continuous with the side walls of groove 16 within the range of insert H. The surfaces 34 and 35 are spaced away from and out of contact with the cable I I, which is out of contact with the dielectric material of block 5 at all points along the surface thereof.

The structure described hereinbefore constitutes an attachment of a single tension cable H to the insulator of block 15. The insulator embodies a second attachment for a member that reacts to the tensile stress of cable I l to hold the insulator in static equilibrium. The second attachment may constitute any suitable structure, depending upon the particular installations of the insulator.

For example, the second embodiment may be the terminal loop 40, Fig. l, of a second cable length 4|. In this case the dielectric block 15 is provided with a second groove 42 which is the same in all particulars as the groove Hi. The groove 42 contains a second insert ll, which is supported in groove 42 in precisely the same manner as the insert 11 of groove IS.

The grooves l6 and 42 are positioned in block l5, spaced apart in the direction of the tension of cables H and 41, and located for the cable loops l2 and A!) to interlock each other. The inside or concave curves of the loops I2 and are thus directed towards each other with a mass of dielectric material between them. The tensile stress of the cables I! and 4| is transmitted as compression stress to the dielectric material of the block l5, and a sufficient mass of dielectric material is provided between the grooves l6 and 42 to support this compression stress.

The axes of both cylindrical bottom-component surfaces of the several grooves l5 and 42 intersect the common line of tension of the cable lengths I! and 4!, and within the block [5 the axes of grooves l 6 and 42 are angularly displaced on the axis of tension of the cables H and 4| at right angles with reference to each other.

The structure disclosed herein presents one practical application of the invention, which is not limited to the specific structure of the disclosure. The scope of the invention is determined by the accompanying claims.

I claim:

1. An electrical insulator, said insulator comprising a block, said block being formed with an arcuate gIOOVe, the groove in transverse section being of rectangular shape to provide a bottom and side walls perpendicular to the bottom, transverse riser faces in the bottom of the groove, said riser faces being arcuately spaced more than 180 degrees, an insert permanently nested in the groove between the riser faces, said insert being of arcuate shape to conform with the groove, said insert having a bottom contoured for contact throughout its entire surface With the groove bottom, said insert having perpendicular side walls contoured for contact throughout their entire surfaces with the groove walls, the ends of said insert being arcuately spaced more than 180 degrees whereby said insert is permanently retained in assembled position in the groove, the arcuate span of the groove between said riser faces being slightly greater than the arcuate span of said insert whereby the ends of said insert are normally spaced slightly from said groove riser faces, said insert being formed throughout its arcuate span with a trough in the exposed surface of the insert, said trough in transverse section being U-shaped, said insert being of heavy construction with the thickness at the bottom and each side being about one-fourth the width of the trough.

2. An electrical insulator for attaching a cable of circular transverse section by means of a loop of the cable, said insulator comprising a dielectric block, said block at its periphery being formed with an arcuate groove, the groove in transverse section being of rectangular shape to provide a bottom and side walls perpendicular to the bottom, the central portion of the groove for an arcuate span exceeding 180 being countersunk,

transverse riser faces in the bottom of the groove defining the ends of the countersunk portion, a metal insert permanently nested in the countersunk portion of the groove, said insert being of arcuate shape to conform with the groove, said insert having a bottom contoured for contact throughout its entire surface with the groove bottom, said insert having perpendicular side walls contoured for contact throughout their entire surfaces with the groove walls, the ends of said insert being arcuately spaced more than whereby said insert is permanently retained in assembled position in the groove, the countersunk portion of the groove being of slightly greater arcuate span than the arcuate span of said insert whereby the ends of said insert are normally spaced slightly from said groove riser faces, said insert being formed throughout its arcuate span with a trough in the exposed surface of the insert, said trough in transverse section being U-shaped with the bottom semicircular and the sides flat and tangential to the bottom, said insert being of heavy construction with the thickness at the bottom and each side being about one-fourth the width of the trough.

, HERMAN KREISLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,284,974 Austin 1- Nov. 19, 1918 1,712,557 Gouverneur May 14, 1929 FOREIGN PATENTS Number Country Date 172,963 Great Britain Sept. 21, 1922 588,186 France Jan. 28, 1925 633,503 France Oct. 24, 1927 774,195 France Sept. 17, 1934 

